Radio receiving apparatus



Patented Der. 19, TQZZ.

Nlill 'STS HENRY M. WTLLIAMSON, OF CHICAGO, ILLINOIS.

RADIO RECEVNG APPARATUS.

Application led September 25, 1922. Serial No. 590,220.

To allwfzom it may concern Be it known that T, HENRY M. VILLIAM- SON, a citizen of the United States, and a resident of the city of Chicago, in the county of Cook and State of llllinois, have invented certain new and useful Improvements in Radio Receiving Apparatus, of which the following is a specification.

This invention is an apparatus having an yaudio-frequency amplifier, or a cascade of such amplifiers, and having means for isolating and excluding from their telephonie receivers static and other wave disturbances, from any source, foreign to the amplified sound waves transmitted thereto and for preventing oscillations in a thermionic amplifier.

The prime object of my invention. broadly stated, is tov provide a radio apparatus with means adapted to filter out static and other waves foreign to the audible sound waves, and thereby isolate-the receiver therefrom and also to exclude the infiuences to which inherent internal undesired oscillations are due.

A further object'of my invention is to provide ameans located between the detector and the receiver` which means is adapted to filter out static from desiredsound waves.

With these endsin view, my invention finds embodiment in certain features of novelty in the construction, combination and arrangement of parts by which the said objects and other objects are attained, all as hereinafter 'fully described with reference to the accompanying drawing and more particularly pointed out in the claims. K

In said drawing is illustrated diagrammatically a radio apparatus in which my invention finds its embodiment.

Similar characters of reference indicate .the same parts in said drawing.

Referring to the drawing. 1 is the antenna, 2 the primary winding of the loose-coupler Ior vario-coupler, 3 the adjustable switch, and 1, a variable condenser approximately .001 m. f.. while 5 represents aground connection. This circuit is known'as the antenna or open circuit, and, as is usual. is capable of adjustment as to resonance for high frequency electro-magnetic Waves of different lengths which are transmitted from a transmitting station. This adjustment simply means that a proper value of capacity (in micro-farads) and a proper value of inductance (in henries) has been attained to allow the passage of waves of predetermined frequencies.

6 indicates the secondary winding of the induction coil, or vario-coupler. Connected to one terminal of this secondary winding is a grid condenser 7, a grid leak 8, and the grid 9 of the detector tube 10. The other terminal of the winding 6 is connectedL to the lighting filament 11 of the same tube. Across the terminals of the secondary coil 6 is connecteda variable condenser 6a, of approximately .0005 m. f. This condenser effectuates sharper tuning of the circuit, which is known as the closed or detector circuit, by giving the proper value of capacity to` that circuit in order to counter-balance the inductance of the seconda-ry winding of the vario-coupler, thereby allowing the high frequency waves to pass to and charge the grid alternately. The grid 9 in the tube 10 acts as a Valve inasmuch as it accumulates chargesof electricity alternating in direction, which charges alternately increase and decrease the resistance of the path between the filament and the plate 12 for the plate circuit current, thereby causing corresponding increases and decreases in the current value of the plate circuit, in which circuit the primary winding 13 of a transformer or induction coil is situated. vThe current for the plate circuit, including Ather` primary winding 13, is furnished by a dry-cell battery of approximately E22 volts, shown at 14. rlhis filament circuit contains a rheo/stat 15 for regulating the current flow from the sixvolt storage battery 16, through the filament 11, through the space in the vacuum of the tube 10 to the pla-te 12, and thence through the primary winding of the transformer 13 to the battery 14. This space appears to be an open, but the functioning of the tube isexplained by the ionic action Within the tube when the filament is heated to incandescency. v

The condenser 17 shunted across the primary winding 13 of the transformer, assists in demagnetizing the core and the winding of the transformer, thereby making this winding more susceptible to high frequency currents and making for clearness. In addition. this condenser oifers a path of low resistance for very high frequency currents. such as are set up by static and other foreign interferences, shunting them outof los the primary winding of the transformer. It will be seen that the current in this plate circuit is of pulsating-direct character. The valve or grid 9, by causing a change of-resistance in the ionic path between the filament and the plate, produces a corresponding change in the current in the plate circuit, but the current always flows 1n one direction.

18 represents the secondary winding of the transformer of which 13 is the primary. Transformers, such as are.ordinarily employed, are usually 4 to 1 up to 10 to 1 ratio. The current flowing through the primary 13, induces into the secondary 18 a current of like character or form, but of higher pressure or voltage. This secondary current or voltage is impressed upon the grid 19 of the amplifying tube 20 and charges it with greater intensity (alternately) than was the case in the previous tube, because now instead of being a feeble current, or pressure, and of very high frequency, this current is of audible frequency with a higher pressure due to the fact that the 22 volt battery made it 22 volts pressure, and, in addition, the transformer stepped it up on a ratio of 4 to 1 or 10 to 1, or whatever ratio is employed, lmaking a much higher pressure for the charge on the grid 19.

In this secondary circuit, including the secondary Winding 18 of the transformer, the grid 19 of the amplifyin tube 20 and and the filament 21, is a conenser 22 and a high resistance 23 in multiple shunted across the secondary of the transformer. The action of this condenser 22 'is to clear out or demagnetize the core of the transformer more rapidly, thereby making it more susceptible to rapid alternatingvcurrents. This, of course, improves the transmission of the audible frequencies, or voice frequencies. In addition to this function, it tends to keep clear,v or fully discharge the grid, at the point of neutrality or zero M. F. and current. This latter action makes for clearness or distinctness of the voice frequencies. Again,

such as internal tube oshigh frequencies, J cillations, static and other foreign dis- `turbing currents find a path of small resistance through the condenser 22 and the currents of high voltages with -high frequencies find-,a path of small resistance through the high resistance .23. Thus the condenser and'high resistance offer a path of small impedance through this shunt, wlthout causing undesired changes in the amount of charge on the rid impressed by the incoming waves. igh frequencies heretofore caused by oscillating tubes, are completely shunted out of the grid by, this shunt. thus making it ossible to employ as many tubes as desired', and to employ a much higher ratio of transformation than has heretofore been used. The .cycle of events is carried on through additional transformers and tubes as the figure shows. The capacity of the condenser, in any given apparatus, should be determined by and in proportion to the reactance due to the inductance of the transformer, it being known in the art that a step-up transformer for audio-frequency possesses a high degree of reactance. As many as seven tubes and Six 'transformers have been successfully employed without internal oscillations, and a very high degree of amplification of frequencies characteristic of the voice frequencies, attained.

A condenser 24, associated with a resistance 25, in each of the intermediate circuits, affords a path of low resistance for static and/other .waves of high frequency. Thiscondenser, furthermore, affords a path of low resistance for waves of high frequency such as are produced by static and other extraneous sources which are, therefore, shunted away from and hence cannot pass through the proximate high-reactance primary winding. Such a condenser, as 17, shunted across the primary winding of a transformer, likewise operates to accumulate these high-frequency waves and thus exclude them from said 'primary winding.

Having described my invention, what T Qclaim and desire tosecure by Letters Patent `1s:-

1.. A thermionic amplifier combined with means for preventing inherent oscillations in the gridcircuit thereof, comprising a high reactance and a condenser shunted across the filament-grid circuit. f

2. A radio apparatus having a thermionic amplifier and containing means for preventing inherent oscillations in said amplifier, including an audio-frequency step-up transformer and a condenser disposed between said amplifierl and said transformer and' shunted across the filament-grid circuit of the apparatus for accumulating the entire static charge of negative electricity developed by said amplifier, the ions andthe gridv of said amplifier constituting a conductive path communicating with said condenser.

3. A radio apparatus having a three-electrode thermionic amplifier and means for preventing inherent oscillations in the filament-grid circuit thereof, including a stepup transformer and, between the secondar winding of said transformer and the ampllfier, a current-qualifying shunt extending across the filament-grid circuit.

4:. A radio apparatus having thermionic amplifiers, and. including a shunting condenser extending across one grid circuitfor preventing oscillations in one amplifier, and another shunting condenser arranged in multiple with a resistance extending across anothery grid circuit for preventing oscilla- 130 .20 put.

3l ,ll-39,495

-5 ordinary ampliiier, the grid of said amplifier being included in a'circuit upon Which the receivedoscillations are im ressed, and means for preventing undesire oscillations in said grid circuit, comprising a condenser .10 having a capacity so proportioned tothe capacity of the grid as to receive and retain the. ionically produced charges which .tend to accumulate on said grid.

6. An audio receiving apparatus having a plurality of thermionicv amplifiers andl an input and an output, and means in the lament-grid circuits of said amplifiers for preventing undesired, amplified and audible internal oscillations from aecting said out- 7. An Aapparatus .for amplifying and clarifying Waves of audible frequency, including a receiving circuit containing the primary Winding of a step-up transformer, 2,5 a second circuit containin the seconda winding of the same trans ormer in Whic the wave -frequency is the same as the Wave n, rfrequency in said primary Winding, a grid in the same circuit as said secondary Windy3er ing, a llainent, a plate and a telephonie re ceiver in another circuit, said grid being appropriately disposed between said lanient and saidplate, and -a condenser short-circuited across 'said second circuit and eri-oper 3,5 ating with the said transformer to prevent inherent oscillations in the filament-grid cir-A 8. An apparatus for amplifying and clari- `fying Waves of audible frequency, includingy 40. a circuit containing a high reactance, a grid' land a filament in serie s, another circuit containing said filament,`a plate and al telephonicreceiver, and a condenser shortcir- 3 -'uited across the filament-grid circuit.

9. An audio amplifying apparatus havingy means for quieting the amplifying element, said apparatus including a source of energy, a plate arranged to attract ions from said source, a grid appropriately disposed 4between said source andsaid plate, and a high reactance in circuit with said grid and said source, said means being additional to said source and said grid, and arranged to receive the ent-ire static charges of electricity develo ed by said source.

A10. n audio receiving apparatus having a plurality of thermionic amplifiers and an input and an output, and means in said apparatus for preventing undesired, amplified and audible internal oscillations from afecting said output. l

l1. An apparatus for amplifying and clarifying Waves of audible frequency, including a receiving circuit containing the primary winding of a step-up transformer, a second circuit containin the secondary Winding of the same trans ormer in which the Wave frequency is the same as the wave frequency in said primary Winding,`va grid in the same circuit as said secondary winding, a filament, a plate and a telephonie receiver in another circuit, said grid being apcuit and operating to prevent inherent csail-- lations inthe filament-grid circuit.`

propriately ,disposed between said/filament and said plate,'and a condenser vand a re- 12. A thermionic amplifier combined With v means-for preventing inherent oscillations therein, including a high reactance and a `condenser and a resistance in multiple shunted across the lament-grid circuit.

In Witness whereof, l have hereunto set my hand and axedmy name this 21st day of September, 1922. L

nnnrtr M. WinLiAMsoit. 

